Bottom Line:
Densities in the larval stages varied among the areas, but the urban area had almost two-fold higher densities in pupae and three-fold higher in adult populations compared with the suburban and rural areas.Study regions, surface area, water depth, water clearance, surface type, and canopy coverage were important factors associated with the presence of Ae. albopictus larvae.Urbanization substantially increased the density, larval development rate, and adult survival time of Ae. albopictus, which in turn potentially increased the vector capacity, and therefore, disease transmissibility.

Affiliation: Key Laboratory of Prevention and Control for Emerging Infectious Diseases of Guangdong Higher Institutes, Department of Pathogen Biology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, China.

ABSTRACT

Introduction: Aedes albopictus is a very invasive and aggressive insect vector that causes outbreaks of dengue fever, chikungunya disease, and yellow fever in many countries. Vector ecology and disease epidemiology are strongly affected by environmental changes. Urbanization is a worldwide trend and is one of the most ecologically modifying phenomena. The purpose of this study is to determine how environmental changes due to urbanization affect the ecology of Aedes albopictus.

Methods: Aquatic habitats and Aedes albopictus larval population surveys were conducted from May to November 2013 in three areas representing rural, suburban, and urban settings in Guangzhou, China. Ae. albopictus adults were collected monthly using BG-Sentinel traps. Ae. albopictus larva and adult life-table experiments were conducted with 20 replicates in each of the three study areas.

Results: The urban area had the highest and the rural area had the lowest number of aquatic habitats that tested positive for Ae. albopictus larvae. Densities in the larval stages varied among the areas, but the urban area had almost two-fold higher densities in pupae and three-fold higher in adult populations compared with the suburban and rural areas. Larvae developed faster and the adult emergence rate was higher in the urban area than in suburban and rural areas. The survival time of adult mosquitoes was also longer in the urban area than it was in suburban and rural areas. Study regions, surface area, water depth, water clearance, surface type, and canopy coverage were important factors associated with the presence of Ae. albopictus larvae.

Conclusions: Urbanization substantially increased the density, larval development rate, and adult survival time of Ae. albopictus, which in turn potentially increased the vector capacity, and therefore, disease transmissibility. Mosquito ecology and its correlation with dengue virus transmission should be compared in different environmental settings.

Mentions:
The study was conducted in three areas that represented urban, suburban, and rural settings in Guangzhou (Figure 1 and Figure S1). Each study area was approximately 1.8 km2. The distance between each area was approximately 24 km. Tonghe (113°19′E, 23°11′N, 31 m above sea level (a.s.l.)) is an urban area with a population density of >3,000 people/km2. The land use types are primarily residential and commercial buildings and public services such as schools and hospitals, filled with trees and grasses. Liangtian (113°23′E, 23°21′N, 25 m a.s.l.) is a suburban area with a population density of approximately 1,000 people/km2, and land use includes a mixture of residential, manufacturing, and farmland. Dengcun (113°33′E, 23°30′N, 42 m a.s.l.) is a rural area and has a population density of <100 people/km2, where land use is primarily agricultural (rice and vegetable planting) and forest.

Mentions:
The study was conducted in three areas that represented urban, suburban, and rural settings in Guangzhou (Figure 1 and Figure S1). Each study area was approximately 1.8 km2. The distance between each area was approximately 24 km. Tonghe (113°19′E, 23°11′N, 31 m above sea level (a.s.l.)) is an urban area with a population density of >3,000 people/km2. The land use types are primarily residential and commercial buildings and public services such as schools and hospitals, filled with trees and grasses. Liangtian (113°23′E, 23°21′N, 25 m a.s.l.) is a suburban area with a population density of approximately 1,000 people/km2, and land use includes a mixture of residential, manufacturing, and farmland. Dengcun (113°33′E, 23°30′N, 42 m a.s.l.) is a rural area and has a population density of <100 people/km2, where land use is primarily agricultural (rice and vegetable planting) and forest.

Bottom Line:
Densities in the larval stages varied among the areas, but the urban area had almost two-fold higher densities in pupae and three-fold higher in adult populations compared with the suburban and rural areas.Study regions, surface area, water depth, water clearance, surface type, and canopy coverage were important factors associated with the presence of Ae. albopictus larvae.Urbanization substantially increased the density, larval development rate, and adult survival time of Ae. albopictus, which in turn potentially increased the vector capacity, and therefore, disease transmissibility.

Affiliation:
Key Laboratory of Prevention and Control for Emerging Infectious Diseases of Guangdong Higher Institutes, Department of Pathogen Biology, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, China.

ABSTRACT

Introduction: Aedes albopictus is a very invasive and aggressive insect vector that causes outbreaks of dengue fever, chikungunya disease, and yellow fever in many countries. Vector ecology and disease epidemiology are strongly affected by environmental changes. Urbanization is a worldwide trend and is one of the most ecologically modifying phenomena. The purpose of this study is to determine how environmental changes due to urbanization affect the ecology of Aedes albopictus.

Methods: Aquatic habitats and Aedes albopictus larval population surveys were conducted from May to November 2013 in three areas representing rural, suburban, and urban settings in Guangzhou, China. Ae. albopictus adults were collected monthly using BG-Sentinel traps. Ae. albopictus larva and adult life-table experiments were conducted with 20 replicates in each of the three study areas.

Results: The urban area had the highest and the rural area had the lowest number of aquatic habitats that tested positive for Ae. albopictus larvae. Densities in the larval stages varied among the areas, but the urban area had almost two-fold higher densities in pupae and three-fold higher in adult populations compared with the suburban and rural areas. Larvae developed faster and the adult emergence rate was higher in the urban area than in suburban and rural areas. The survival time of adult mosquitoes was also longer in the urban area than it was in suburban and rural areas. Study regions, surface area, water depth, water clearance, surface type, and canopy coverage were important factors associated with the presence of Ae. albopictus larvae.

Conclusions: Urbanization substantially increased the density, larval development rate, and adult survival time of Ae. albopictus, which in turn potentially increased the vector capacity, and therefore, disease transmissibility. Mosquito ecology and its correlation with dengue virus transmission should be compared in different environmental settings.